JS notes (execution Environment, scope)

1. The execution environment corresponds to a variable object, including all variables and functions of the environment.

2. The execution environment can also be a function, each function has its own execution environment, at this time, the variable object of the function is the active object, and at the beginning there is only one variable, named parameter, arguments object.

3. When the code is run, the scope chain of the variable object is created, the most front-end of the scope is the variable object of the current execution environment, and when the code does not find an identifier in the current variable environment, the next variable object is searched until it is found, and the last variable object is the global execution environment variable object.

JS notes (execution Environment, scope)